Peel and Place Dressing For Negative-Pressure Therapy

ABSTRACT

A dressing for treating a tissue site with negative pressure may comprise a cover having an adhesive, a manifold, a perforated polymer film, and a perforated silicone gel having a treatment aperture. The cover, the manifold, the perforated polymer film, and the perforated silicone gel may be assembled in a stacked relationship with the cover and the perforated silicone gel enclosing the manifold. The perforated polymer film may be at least partially exposed through the treatment aperture, and at least some of the adhesive may be exposed through the perforated silicone around the treatment aperture.

RELATED APPLICATIONS

This application claims the benefit, under 35 U.S.C. § 119(e), of thefiling of U.S. Provisional Patent Application Ser. No. 62/650,572,entitled “ASSEMBLY FEATURES AND METHODS FOR A PEEL-AND-PLACE DRESSINGFOR USE WITH NEGATIVE-PRESSURE TREATMENT,” filed Mar. 30, 2018; U.S.Provisional Patent Application Ser. No. 62/633,438, entitled “COMPOSITEDRESSINGS FOR IMPROVED GRANULATION AND REDUCED MACERATION WITHNEGATIVE-PRESSURE TREATMENT,” filed Feb. 21, 2018; U.S. ProvisionalPatent Application Ser. No. 62/623,325, entitled “METHODS FORMANUFACTURING AND ASSEMBLING DUAL MATERIAL TISSUE INTERFACE FORNEGATIVE-PRESSURE THERAPY,” filed Jan. 29, 2018; U.S. Provisional PatentApplication Ser. No. 62/625,704, entitled “CUSTOMIZABLE COMPOSITEDRESSINGS FOR IMPROVED GRANULATION AND REDUCED MACERATION WITHNEGATIVE-PRESSURE TREATMENT,” filed Feb. 2, 2018; U.S. ProvisionalPatent Application Ser. No. 62/616,244, entitled “COMPOSITE DRESSINGSFOR IMPROVED GRANULATION AND REDUCED MACERATION WITH NEGATIVE-PRESSURETREATMENT,” filed Jan. 11, 2018; U.S. Provisional Patent ApplicationSer. No. 62/615,821, entitled “METHODS FOR MANUFACTURING AND ASSEMBLINGDUAL MATERIAL TISSUE INTERFACE FOR NEGATIVE-PRESSURE THERAPY,” filedJan. 10, 2018; U.S. Provisional Patent Application Ser. No. 62/613,494,entitled “PEEL AND PLACE DRESSING FOR THICK EXUDATE AND INSTILLATION,”filed Jan. 4, 2018; U.S. Provisional Patent Application Ser. No.62/592,950, entitled “MULTI-LAYER WOUND FILLER FOR EXTENDED WEAR TIME,”filed Nov. 30, 2017; U.S. Provisional Patent Application Ser. No.62/576,498, entitled “SYSTEMS, APPARATUSES, AND METHODS FORNEGATIVE-PRESSURE TREATMENT WITH REDUCED TISSUE IN-GROWTH,” filed Oct.24, 2017; U.S. Provisional Patent Application Ser. No. 62/565,754,entitled “COMPOSITE DRESSINGS FOR IMPROVED GRANULATION AND REDUCEDMACERATION WITH NEGATIVE-PRESSURE TREATMENT,” filed Sep. 29, 2017; U.S.Provisional Patent Application Ser. No. 62/516,540, entitled “TISSUECONTACT INTERFACE,” filed Jun. 7, 2017; U.S. Provisional PatentApplication Ser. No. 62/516,550, entitled “COMPOSITE DRESSINGS FORIMPROVED GRANULATION AND REDUCED MACERATION WITH NEGATIVE-PRESSURETREATMENT,” filed Jun. 7, 2017; and U.S. Provisional Patent ApplicationSer. No. 62/516,566, entitled “COMPOSITE DRESSINGS FOR IMPROVEDGRANULATION AND REDUCED MACERATION WITH NEGATIVE-PRESSURE TREATMENT,”filed Jun. 7, 2017, each of which is incorporated herein by referencefor all purposes.

TECHNICAL FIELD

The invention set forth in the appended claims relates generally totissue treatment systems and more particularly, but without limitation,to dressings for tissue treatment and methods of using the dressings fortissue treatment with negative pressure.

BACKGROUND

Clinical studies and practice have shown that reducing pressure inproximity to a tissue site can augment and accelerate growth of newtissue at the tissue site. The applications of this phenomenon arenumerous, but it has proven particularly advantageous for treatingwounds. Regardless of the etiology of a wound, whether trauma, surgery,or another cause, proper care of the wound is important to the outcome.Treatment of wounds or other tissue with reduced pressure may becommonly referred to as “negative-pressure therapy,” but is also knownby other names, including “negative-pressure wound therapy,”“reduced-pressure therapy,” “vacuum therapy,” “vacuum-assisted closure,”and “topical negative-pressure,” for example. Negative-pressure therapymay provide a number of benefits, including migration of epithelial andsubcutaneous tissues, improved blood flow, and micro-deformation oftissue at a wound site. Together, these benefits can increasedevelopment of granulation tissue and reduce healing times.

There is also widespread acceptance that cleansing a tissue site can behighly beneficial for new tissue growth. For example, a wound or acavity can be washed out with a liquid solution for therapeuticpurposes. These practices are commonly referred to as “irrigation” and“lavage” respectively. “Instillation” is another practice that generallyrefers to a process of slowly introducing fluid to a tissue site andleaving the fluid for a prescribed period of time before removing thefluid. For example, instillation of topical treatment solutions over awound bed can be combined with negative-pressure therapy to furtherpromote wound healing by loosening soluble contaminants in a wound bedand removing infectious material. As a result, soluble bacterial burdencan be decreased, contaminants removed, and the wound cleansed.

While the clinical benefits of negative-pressure therapy and/orinstillation therapy are widely known, improvements to therapy systems,components, and processes may benefit healthcare providers and patients.

BRIEF SUMMARY

New and useful systems, apparatuses, and methods for treating tissue ina negative-pressure therapy environment are set forth in the appendedclaims. Illustrative embodiments are also provided to enable a personskilled in the art to make and use the claimed subject matter.

For example, in some embodiments, a dressing for treating tissue may bea composite of dressing layers, including a sealing layer, a fluidcontrol layer, a manifold and a cover. In some examples, the sealinglayer may comprise or consist essentially of a layer of perforated gel,such as a silicone gel. A central area of the gel may be removed todefine a treatment aperture. The fluid control layer may comprise orconsist essentially of a polyurethane film having fluid restrictions,such as fenestrations in the film. The film may be backed with anacrylic adhesive in some embodiments. The manifold may be a reticulatedfoam in some examples, and the polyurethane film may be laminated to themanifold or the acrylic adhesive on the polyurethane film can bond thetwo together. In some examples, the polyurethane film may be laminatedto the manifold and then cut to a desired size and shape, which cansimplify manufacturing processes.

In some examples, the manifold and the fluid control layer may have adiameter that is larger than the treatment aperture, so that the edge ofthe manifold is not exposed when assembled and applied to a tissue site.The fluid control layer may be disposed over the treatment aperture sothat a substantial number of the fluid restrictions are aligned with thetreatment aperture. For example, the manifold and fluid control layermay be substantially aligned with the treatment aperture, although awide tolerance may be acceptable. The manifold and the fluid controllayer may overlay an area of the sealing layer around the treatmentaperture, and the sealing layer may have an adhesive in the overlay areato secure the manifold, the fluid control layer, or both. The cover maybe positioned over the assembled manifold and fluid control layer andadhered to the sealing layer to enclose the manifold.

In some embodiments, the sealing layer may comprise or consistessentially of a layer of perforated gel, such as a silicone gel, havingperforations continuously distributed across the sealing layer. Fluidrestrictions in the fluid control layer may be disposed within theperforations, which can provide similar functionality to the treatmentaperture while increasing the surface area of the sealing layer.

More generally, a dressing for treating a tissue site with negativepressure may comprise a sealing layer having a treatment aperture and aplurality of perforations around the treatment aperture, and a fluidcontrol layer having a plurality of fluid restrictions aligned with thetreatment aperture. A manifold may be disposed adjacent to the fluidrestrictions, and a cover comprising a non-porous film may be disposedover the manifold and coupled to the sealing layer around the manifold.The cover may additionally have a pressure-sensitive adhesive disposedadjacent to the plurality of perforations. In more particularembodiments, the fluid control layer may comprise or consist essentiallyof a polyurethane film. The sealing layer may be formed from a gel, suchas a silicone gel in some embodiments.

In some examples, the manifold may have a first edge defining a manifoldface adjacent to the fluid control layer, and the fluid control layermay have a second edge defining a fluid control face adjacent to themanifold face. The fluid control face and the manifold face may have asimilar shape in some embodiments. The manifold face may be at least aslarge as the fluid control face, and the fluid control face may belarger than the treatment aperture. In more specific examples, at leastone of the manifold and the fluid control layer may be coupled to amargin around the treatment aperture.

Alternatively, other example embodiments of a dressing for treating atissue site with negative pressure may comprise a manifold and a fluidcontrol layer comprising a plurality of fluid restrictions adjacent tothe manifold. A sealing layer comprising a plurality of perforations maybe disposed adjacent to the fluid control layer and at least some of theperforations can be aligned with more than one of the fluidrestrictions. A cover comprising a non-porous film may be disposed overthe manifold and coupled to the sealing layer around the manifold. Thecover may additionally have a pressure-sensitive adhesive disposedadjacent to the plurality of perforations. In more particularembodiments, the fluid control layer may comprise or consist essentiallyof a polyurethane film. The sealing layer may be formed from a gel, suchas a silicone gel in some embodiments.

In more particular examples, the fluid restrictions may comprise slits,which may have a length of about 2 millimeters to about 5 millimeters.Perforations in the sealing layer may be circular, having a diametersufficiently large to align with more than one of the fluidrestrictions. For example, a diameter in a range of about 7 millimetersto about 9 millimeters may be suitable for some configurations.

In some embodiments, a dressing for treating a tissue site with negativepressure may comprise a cover having an adhesive, a manifold, aperforated polymer film, and a perforated silicone gel having atreatment aperture. The cover, the manifold, the perforated polymerfilm, and the perforated silicone gel may be assembled in a stackedrelationship with the cover and the perforated silicone gel enclosingthe manifold. The perforated polymer film may be at least partiallyexposed through the treatment aperture, and at least some of theadhesive may be exposed through the perforated silicone around thetreatment aperture.

A dressing for treating a tissue site with negative pressure maycomprise a manifold, a gel layer, a fluid control layer, and a cover insome embodiments. The gel layer may comprise an open central window anda plurality of openings around the open central window. The fluidcontrol layer may extend across the open central window and comprise aplurality of fluid restrictions. The cover may comprise a non-porousfilm and a pressure-sensitive adhesive, and the non-porous film may bedisposed over the manifold and coupled to the gel layer around themanifold, and the pressure-sensitive adhesive may be disposed adjacentto the plurality of perforations.

In some embodiments, a dressing for treating a tissue site with negativepressure may comprise a foam manifold for the passage of negativepressure and passage of wound fluid; a lower surface having an open areafor delivery of negative pressure and passage of wound fluid via themanifold, the open area being surrounded by a drape area for sealing totissue, the drape area having an adhesive and not including openings forthe passage of negative pressure via the manifold; and a polymer filmwound contact layer extending across the open area in the lower surfaceand having openings for the passage of negative pressure and wound fluidinto the foam manifold. The dressing may further comprise a cover insome embodiments, the cover comprising a drape disposed over themanifold and coupled to the drape area around the manifold.

Objectives, advantages, and a preferred mode of making and using theclaimed subject matter may be understood best by reference to theaccompanying drawings in conjunction with the following detaileddescription of illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram of an example embodiment of atherapy system that can provide negative-pressure treatment andinstillation treatment in accordance with this specification;

FIG. 2 is an assembly view of an example of a dressing, illustratingadditional details that may be associated with some example embodimentsof the therapy system of FIG. 1;

FIG. 3 is a top view of the example dressing of FIG. 2;

FIG. 4 is a bottom view of the example dressing of FIG. 2;

FIG. 5 is an assembly view of another example of a dressing,illustrating additional details that may be associated with some exampleembodiment of the therapy system of FIG. 1;

FIG. 6 is a schematic view of an example configuration of fluidrestrictions in a layer that may be associated with some embodiments ofthe dressing of FIG. 2 or FIG. 5;

FIG. 7 is a schematic view of an example configuration of apertures in alayer that may be associated with some embodiments of the dressing ofFIG. 5; and

FIG. 8 is a schematic view of the example layer of FIG. 6 overlaid onthe example layer of FIG. 7.

DESCRIPTION OF EXAMPLE EMBODIMENTS

The following description of example embodiments provides informationthat enables a person skilled in the art to make and use the subjectmatter set forth in the appended claims, but it may omit certain detailsalready well-known in the art. The following detailed description is,therefore, to be taken as illustrative and not limiting.

The example embodiments may also be described herein with reference tospatial relationships between various elements or to the spatialorientation of various elements depicted in the attached drawings. Ingeneral, such relationships or orientation assume a frame of referenceconsistent with or relative to a patient in a position to receivetreatment. However, as should be recognized by those skilled in the art,this frame of reference is merely a descriptive expedient rather than astrict prescription.

FIG. 1 is a simplified functional block diagram of an example embodimentof a therapy system 100 that can provide negative-pressure therapy withinstillation of topical treatment solutions to a tissue site inaccordance with this specification.

The term “tissue site” in this context broadly refers to a wound,defect, or other treatment target located on or within tissue,including, but not limited to, bone tissue, adipose tissue, muscletissue, neural tissue, dermal tissue, vascular tissue, connectivetissue, cartilage, tendons, or ligaments. A wound may include chronic,acute, traumatic, subacute, and dehisced wounds, partial-thicknessburns, ulcers (such as diabetic, pressure, or venous insufficiencyulcers), flaps, and grafts, for example. The term “tissue site” may alsorefer to areas of any tissue that are not necessarily wounded ordefective, but are instead areas in which it may be desirable to add orpromote the growth of additional tissue. For example, negative pressuremay be applied to a tissue site to grow additional tissue that may beharvested and transplanted.

The therapy system 100 may include a source or supply of negativepressure, such as a negative-pressure source 105, and one or moredistribution components. A distribution component is preferablydetachable and may be disposable, reusable, or recyclable. A dressing,such as a dressing 110, and a fluid container, such as a container 115,are examples of distribution components that may be associated with someexamples of the therapy system 100. As illustrated in the example ofFIG. 1, the dressing 110 may comprise or consist essentially of a tissueinterface 120, a cover 125, or both in some embodiments.

A fluid conductor is another illustrative example of a distributioncomponent. A “fluid conductor,” in this context, broadly includes atube, pipe, hose, conduit, or other structure with one or more lumina oropen pathways adapted to convey a fluid between two ends. Typically, atube is an elongated, cylindrical structure with some flexibility, butthe geometry and rigidity may vary. Moreover, some fluid conductors maybe molded into or otherwise integrally combined with other components.Distribution components may also include or comprise interfaces or fluidports to facilitate coupling and de-coupling other components. In someembodiments, for example, a dressing interface may facilitate coupling afluid conductor to the dressing 110. For example, such a dressinginterface may be a SENSAT.R.A.C.™ Pad available from Kinetic Concepts,Inc. of San Antonio, Tex.

The therapy system 100 may also include a regulator or controller, suchas a controller 130. Additionally, the therapy system 100 may includesensors to measure operating parameters and provide feedback signals tothe controller 130 indicative of the operating parameters. Asillustrated in FIG. 1, for example, the therapy system 100 may include afirst sensor 135 and a second sensor 140 coupled to the controller 130.

The therapy system 100 may also include a source of instillationsolution. For example, a solution source 145 may be fluidly coupled tothe dressing 110, as illustrated in the example embodiment of FIG. 1.The solution source 145 may be fluidly coupled to a positive-pressuresource such as a positive-pressure source 150, a negative-pressuresource such as the negative-pressure source 105, or both in someembodiments. A regulator, such as an instillation regulator 155, mayalso be fluidly coupled to the solution source 145 and the dressing 110to ensure proper dosage of instillation solution (e.g. saline) to atissue site. For example, the instillation regulator 155 may comprise apiston that can be pneumatically actuated by the negative-pressuresource 105 to draw instillation solution from the solution source duringa negative-pressure interval and to instill the solution to a dressingduring a venting interval. Additionally or alternatively, the controller130 may be coupled to the negative-pressure source 105, thepositive-pressure source 150, or both, to control dosage of instillationsolution to a tissue site. In some embodiments, the instillationregulator 155 may also be fluidly coupled to the negative-pressuresource 105 through the dressing 110, as illustrated in the example ofFIG. 1.

Some components of the therapy system 100 may be housed within or usedin conjunction with other components, such as sensors, processing units,alarm indicators, memory, databases, software, display devices, or userinterfaces that further facilitate therapy. For example, in someembodiments, the negative-pressure source 105 may be combined with thecontroller 130, the solution source 145, and other components into atherapy unit.

In general, components of the therapy system 100 may be coupled directlyor indirectly. For example, the negative-pressure source 105 may bedirectly coupled to the container 115 and may be indirectly coupled tothe dressing 110 through the container 115. Coupling may include fluid,mechanical, thermal, electrical, or chemical coupling (such as achemical bond), or some combination of coupling in some contexts. Forexample, the negative-pressure source 105 may be electrically coupled tothe controller 130 and may be fluidly coupled to one or moredistribution components to provide a fluid path to a tissue site. Insome embodiments, components may also be coupled by virtue of physicalproximity, being integral to a single structure, or being formed fromthe same piece of material.

A negative-pressure supply, such as the negative-pressure source 105,may be a reservoir of air at a negative pressure or may be a manual orelectrically-powered device, such as a vacuum pump, a suction pump, awall suction port available at many healthcare facilities, or amicro-pump, for example. “Negative pressure” generally refers to apressure less than a local ambient pressure, such as the ambientpressure in a local environment external to a sealed therapeuticenvironment. In many cases, the local ambient pressure may also be theatmospheric pressure at which a tissue site is located. Alternatively,the pressure may be less than a hydrostatic pressure associated withtissue at the tissue site. Unless otherwise indicated, values ofpressure stated herein are gauge pressures. References to increases innegative pressure typically refer to a decrease in absolute pressure,while decreases in negative pressure typically refer to an increase inabsolute pressure. While the amount and nature of negative pressureprovided by the negative-pressure source 105 may vary according totherapeutic requirements, the pressure is generally a low vacuum, alsocommonly referred to as a rough vacuum, between −5 mm Hg (−667 Pa) and−500 mm Hg (−66.7 kPa). Common therapeutic ranges are between −50 mm Hg(−6.7 kPa) and −300 mm Hg (−39.9 kPa).

The container 115 is representative of a container, canister, pouch, orother storage component, which can be used to manage exudates and otherfluids withdrawn from a tissue site. In many environments, a rigidcontainer may be preferred or required for collecting, storing, anddisposing of fluids. In other environments, fluids may be properlydisposed of without rigid container storage, and a re-usable containercould reduce waste and costs associated with negative-pressure therapy.

A controller, such as the controller 130, may be a microprocessor orcomputer programmed to operate one or more components of the therapysystem 100, such as the negative-pressure source 105. In someembodiments, for example, the controller 130 may be a microcontroller,which generally comprises an integrated circuit containing a processorcore and a memory programmed to directly or indirectly control one ormore operating parameters of the therapy system 100. Operatingparameters may include the power applied to the negative-pressure source105, the pressure generated by the negative-pressure source 105, or thepressure distributed to the tissue interface 120, for example. Thecontroller 130 is also preferably configured to receive one or moreinput signals, such as a feedback signal, and programmed to modify oneor more operating parameters based on the input signals.

Sensors, such as the first sensor 135 and the second sensor 140, aregenerally known in the art as any apparatus operable to detect ormeasure a physical phenomenon or property, and generally provide asignal indicative of the phenomenon or property that is detected ormeasured. For example, the first sensor 135 and the second sensor 140may be configured to measure one or more operating parameters of thetherapy system 100. In some embodiments, the first sensor 135 may be atransducer configured to measure pressure in a pneumatic pathway andconvert the measurement to a signal indicative of the pressure measured.In some embodiments, for example, the first sensor 135 may be apiezo-resistive strain gauge. The second sensor 140 may optionallymeasure operating parameters of the negative-pressure source 105, suchas a voltage or current, in some embodiments. Preferably, the signalsfrom the first sensor 135 and the second sensor 140 are suitable as aninput signal to the controller 130, but some signal conditioning may beappropriate in some embodiments. For example, the signal may need to befiltered or amplified before it can be processed by the controller 130.Typically, the signal is an electrical signal, but may be represented inother forms, such as an optical signal.

The tissue interface 120 can be generally adapted to partially or fullycontact a tissue site. The tissue interface 120 may take many forms, andmay have many sizes, shapes, or thicknesses, depending on a variety offactors, such as the type of treatment being implemented or the natureand size of a tissue site. For example, the size and shape of the tissueinterface 120 may be adapted to the contours of deep and irregularshaped tissue sites. Any or all of the surfaces of the tissue interface120 may have an uneven, coarse, or jagged profile.

In some embodiments, the tissue interface 120 may comprise or consistessentially of a manifold. A manifold in this context may comprise orconsist essentially of a means for collecting or distributing fluidacross the tissue interface 120 under pressure. For example, a manifoldmay be adapted to receive negative pressure from a source and distributenegative pressure through multiple apertures across the tissue interface120, which may have the effect of collecting fluid from across a tissuesite and drawing the fluid toward the source. In some embodiments, thefluid path may be reversed or a secondary fluid path may be provided tofacilitate delivering fluid, such as fluid from a source of instillationsolution, across a tissue site.

In some embodiments, the cover 125 may provide a bacterial barrier andprotection from physical trauma. The cover 125 may also be constructedfrom a material that can reduce evaporative losses and provide a fluidseal between two components or two environments, such as between atherapeutic environment and a local external environment. The cover 125may comprise or consist of, for example, an elastomeric film or membranethat can provide a seal adequate to maintain a negative pressure at atissue site for a given negative-pressure source. The cover 125 may havea high moisture-vapor transmission rate (MVTR) in some applications. Forexample, the MVTR may be at least 250 grams per square meter pertwenty-four hours in some embodiments, measured using an upright cuptechnique according to ASTM E96/E96M Upright Cup Method at 38° C. and10% relative humidity (RH). In some embodiments, an MVTR up to 5,000grams per square meter per twenty-four hours may provide effectivebreathability and mechanical properties.

In some example embodiments, the cover 125 may be a non-porous polymerdrape or film, such as a polyurethane film, that is permeable to watervapor but impermeable to liquid. Such drapes typically have a thicknessin the range of 25-50 microns. For permeable materials, the permeabilitygenerally should be low enough that a desired negative pressure may bemaintained. The cover 125 may comprise, for example, one or more of thefollowing materials: polyurethane (PU), such as hydrophilicpolyurethane; cellulosics; hydrophilic polyamides; polyvinyl alcohol;polyvinyl pyrrolidone; hydrophilic acrylics; silicones, such ashydrophilic silicone elastomers; natural rubbers; polyisoprene; styrenebutadiene rubber; chloroprene rubber; polybutadiene; nitrile rubber;butyl rubber; ethylene propylene rubber; ethylene propylene dienemonomer; chlorosulfonated polyethylene; polysulfide rubber; ethylenevinyl acetate (EVA); co-polyester; and polyether block polymidecopolymers. Such materials are commercially available as, for example,Tegaderm® drape, commercially available from 3M Company, MinneapolisMinn.; polyurethane (PU) drape, commercially available from AveryDennison Corporation, Pasadena, Calif.; polyether block polyamidecopolymer (PEBAX), for example, from Arkema S.A., Colombes, France; andInspire 2301 and Inpsire 2327 polyurethane films, commercially availablefrom Expopack Advanced Coatings, Wrexham, United Kingdom. In someembodiments, the cover 125 may comprise INSPIRE 2301 having an MVTR(upright cup technique) of 2600 g/m²/24 hours and a thickness of about30 microns.

An attachment device may be used to attach the cover 125 to anattachment surface, such as undamaged epidermis, a gasket, or anothercover. The attachment device may take many forms. For example, anattachment device may be a medically-acceptable, pressure-sensitiveadhesive configured to bond the cover 125 to epidermis around a tissuesite. In some embodiments, for example, some or all of the cover 125 maybe coated with an adhesive, such as an acrylic adhesive, which may havea coating weight of about 25-65 grams per square meter (g.s.m.). Thickeradhesives, or combinations of adhesives, may be applied in someembodiments to improve the seal and reduce leaks. Other exampleembodiments of an attachment device may include a double-sided tape,paste, hydrocolloid, hydrogel, silicone gel, or organogel.

The solution source 145 may also be representative of a container,canister, pouch, bag, or other storage component, which can provide asolution for instillation therapy. Compositions of solutions may varyaccording to a prescribed therapy, but examples of solutions that may besuitable for some prescriptions include hypochlorite-based solutions,silver nitrate (0.5%), sulfur-based solutions, biguanides, cationicsolutions, and isotonic solutions.

In operation, the tissue interface 120 may be placed within, over, on,or otherwise proximate to a tissue site. If the tissue site is a wound,for example, the tissue interface 120 may partially or completely fillthe wound, or it may be placed over the wound. The cover 125 may beplaced over the tissue interface 120 and sealed to an attachment surfacenear a tissue site. For example, the cover 125 may be sealed toundamaged epidermis peripheral to a tissue site. Thus, the dressing 110can provide a sealed therapeutic environment proximate to a tissue site,substantially isolated from the external environment, and thenegative-pressure source 105 can reduce pressure in the sealedtherapeutic environment.

The fluid mechanics of using a negative-pressure source to reducepressure in another component or location, such as within a sealedtherapeutic environment, can be mathematically complex. However, thebasic principles of fluid mechanics applicable to negative-pressuretherapy and instillation are generally well-known to those skilled inthe art, and the process of reducing pressure may be describedillustratively herein as “delivering,” “distributing,” or “generating”negative pressure, for example.

In general, exudate and other fluid flow toward lower pressure along afluid path. Thus, the term “downstream” typically implies something in afluid path relatively closer to a source of negative pressure or furtheraway from a source of positive pressure. Conversely, the term “upstream”implies something relatively further away from a source of negativepressure or closer to a source of positive pressure. Similarly, it maybe convenient to describe certain features in terms of fluid “inlet” or“outlet” in such a frame of reference. This orientation is generallypresumed for purposes of describing various features and componentsherein. However, the fluid path may also be reversed in someapplications, such as by substituting a positive-pressure source for anegative-pressure source, and this descriptive convention should not beconstrued as a limiting convention.

Negative pressure applied across the tissue site through the tissueinterface 120 in the sealed therapeutic environment can inducemacro-strain and micro-strain in the tissue site. Negative pressure canalso remove exudate and other fluid from a tissue site, which can becollected in container 115.

In some embodiments, the controller 130 may receive and process datafrom one or more sensors, such as the first sensor 135. The controller130 may also control the operation of one or more components of thetherapy system 100 to manage the pressure delivered to the tissueinterface 120. In some embodiments, controller 130 may include an inputfor receiving a desired target pressure and may be programmed forprocessing data relating to the setting and inputting of the targetpressure to be applied to the tissue interface 120. In some exampleembodiments, the target pressure may be a fixed pressure value set by anoperator as the target negative pressure desired for therapy at a tissuesite and then provided as input to the controller 130. The targetpressure may vary from tissue site to tissue site based on the type oftissue forming a tissue site, the type of injury or wound (if any), themedical condition of the patient, and the preference of the attendingphysician. After selecting a desired target pressure, the controller 130can operate the negative-pressure source 105 in one or more controlmodes based on the target pressure and may receive feedback from one ormore sensors to maintain the target pressure at the tissue interface120.

In some embodiments, the controller 130 may have a continuous pressuremode, in which the negative-pressure source 105 is operated to provide aconstant target negative pressure for the duration of treatment or untilmanually deactivated. Additionally or alternatively, the controller mayhave an intermittent pressure mode. For example, the controller 130 canoperate the negative-pressure source 105 to cycle between a targetpressure and atmospheric pressure. For example, the target pressure maybe set at a value of 135 mmHg for a specified period of time (e.g., 5min), followed by a specified period of time (e.g., 2 min) ofdeactivation. The cycle can be repeated by activating thenegative-pressure source 105, which can form a square wave patternbetween the target pressure and atmospheric pressure.

In some example embodiments, the increase in negative-pressure fromambient pressure to the target pressure may not be instantaneous. Forexample, the negative-pressure source 105 and the dressing 110 may havean initial rise time. The initial rise time may vary depending on thetype of dressing and therapy equipment being used. For example, theinitial rise time for one therapy system may be in a range of about20-30 mmHg/second and in a range of about 5-10 mmHg/second for anothertherapy system. If the therapy system 100 is operating in anintermittent mode, the repeating rise time may be a value substantiallyequal to the initial rise time.

In some example dynamic pressure control modes, the target pressure canvary with time. For example, the target pressure may vary in the form ofa triangular waveform, varying between a negative pressure of 50 and 135mmHg with a rise time set at a rate of +25 mmHg/min. and a descent timeset at −25 mmHg/min. In other embodiments of the therapy system 100, thetriangular waveform may vary between negative pressure of 25 and 135mmHg with a rise time set at a rate of +30 mmHg/min and a descent timeset at −30 mmHg/min.

In some embodiments, the controller 130 may control or determine avariable target pressure in a dynamic pressure mode, and the variabletarget pressure may vary between a maximum and minimum pressure valuethat may be set as an input prescribed by an operator as the range ofdesired negative pressure. The variable target pressure may also beprocessed and controlled by the controller 130, which can vary thetarget pressure according to a predetermined waveform, such as atriangular waveform, a sine waveform, or a saw-tooth waveform. In someembodiments, the waveform may be set by an operator as the predeterminedor time-varying negative pressure desired for therapy.

In some embodiments, the controller 130 may receive and process data,such as data related to instillation solution provided to the tissueinterface 120. Such data may include the type of instillation solutionprescribed by a clinician, the volume of fluid or solution to beinstilled to a tissue site (“fill volume”), and the amount of timeprescribed for leaving solution at a tissue site (“dwell time”) beforeapplying a negative pressure to the tissue site. The fill volume may be,for example, between 10 and 500 mL, and the dwell time may be betweenone second to 30 minutes. The controller 130 may also control theoperation of one or more components of the therapy system 100 to instillsolution. For example, the controller 130 may manage fluid distributedfrom the solution source 145 to the tissue interface 120. In someembodiments, fluid may be instilled to a tissue site by applying anegative pressure from the negative-pressure source 105 to reduce thepressure at the tissue site, drawing solution into the tissue interface120. In some embodiments, solution may be instilled to a tissue site byapplying a positive pressure from the positive-pressure source 160 tomove solution from the solution source 145 to the tissue interface 120.Additionally or alternatively, the solution source 145 may be elevatedto a height sufficient to allow gravity to move solution into the tissueinterface 120.

The controller 130 may also control the fluid dynamics of instillationby providing a continuous flow of solution or an intermittent flow ofsolution. Negative pressure may be applied to provide either continuousflow or intermittent flow of solution. The application of negativepressure may be implemented to provide a continuous pressure mode ofoperation to achieve a continuous flow rate of instillation solutionthrough the tissue interface 120, or it may be implemented to provide adynamic pressure mode of operation to vary the flow rate of instillationsolution through the tissue interface 120. Alternatively, theapplication of negative pressure may be implemented to provide anintermittent mode of operation to allow instillation solution to dwellat the tissue interface 120. In an intermittent mode, a specific fillvolume and dwell time may be provided depending, for example, on thetype of tissue site being treated and the type of dressing beingutilized. After or during instillation of solution, negative-pressuretreatment may be applied. The controller 130 may be utilized to select amode of operation and the duration of the negative pressure treatmentbefore commencing another instillation cycle.

FIG. 2 is an assembly view of an example of the dressing 110 of FIG. 1,illustrating additional details that may be associated with someembodiments in which the tissue interface 120 comprises more than onelayer. In the example of FIG. 2, the tissue interface 120 comprises afirst layer 205, a second layer 210, and a third layer 215. In someembodiments, the first layer 205 may be disposed adjacent to the secondlayer 210, and the third layer 215 may also be disposed adjacent to thesecond layer 210 opposite the first layer 205. For example, the firstlayer 205 and the second layer 210 may be stacked so that the firstlayer 205 is in contact with the second layer 210. The first layer 205may also be bonded to the second layer 210 in some embodiments. In someembodiments, the second layer 210 may be coextensive with a face of thefirst layer 205. In some embodiments, at least some portion of the thirdlayer 215 may be bonded to the second layer 210.

The first layer 205 generally comprises or consists essentially of amanifold or a manifold layer, which provides a means for collecting ordistributing fluid across the tissue interface 120 under pressure. Forexample, the first layer 205 may be adapted to receive negative pressurefrom a source and distribute negative pressure through multipleapertures across the tissue interface 120, which may have the effect ofcollecting fluid from across a tissue site and drawing the fluid towardthe source. In some embodiments, the fluid path may be reversed or asecondary fluid path may be provided to facilitate delivering fluid,such as from a source of instillation solution, across the tissueinterface 120.

In some illustrative embodiments, the pathways of the first layer 205may be interconnected to improve distribution or collection of fluids.In some illustrative embodiments, the first layer 205 may comprise orconsist essentially of a porous material having interconnected fluidpathways. Examples of suitable porous material that comprise or can beadapted to form interconnected fluid pathways (e.g., channels) mayinclude cellular foam, including open-cell foam such as reticulatedfoam; porous tissue collections; and other porous material such as gauzeor felted mat that generally include pores, edges, and/or walls.Liquids, gels, and other foams may also include or be cured to includeapertures and fluid pathways. In some embodiments, the first layer 205may additionally or alternatively comprise projections that forminterconnected fluid pathways. For example, the first layer 205 may bemolded to provide surface projections that define interconnected fluidpathways.

In some embodiments, the first layer 205 may comprise or consistessentially of a reticulated foam having pore sizes and free volume thatmay vary according to needs of a prescribed therapy. For example, areticulated foam having a free volume of at least 90% may be suitablefor many therapy applications, and a foam having an average pore size ina range of 400-600 microns may be particularly suitable for some typesof therapy. The tensile strength of the first layer 205 may also varyaccording to needs of a prescribed therapy. For example, the tensilestrength of a foam may be increased for instillation of topicaltreatment solutions. The 25% compression load deflection of the firstlayer 205 may be at least 0.35 pounds per square inch, and the 65%compression load deflection may be at least 0.43 pounds per square inch.In some embodiments, the tensile strength of the first layer 205 may beat least 10 pounds per square inch. The first layer 205 may have a tearstrength of at least 2.5 pounds per inch. In some embodiments, the firstlayer 205 may be a foam comprised of polyols such as polyester orpolyether, isocyanate such as toluene diisocyanate, and polymerizationmodifiers such as amines and tin compounds. In some examples, the firstlayer 205 may be a reticulated polyurethane foam such as used inGRANUFOAM™ dressing or V.A.C. VERAFLO™ dressing, both available from KCIof San Antonio, Tex.

Other suitable materials for the first layer 205 may include non-wovenfabrics (Libeltex, Freudenberg), three-dimensional (3D) polymericstructures (molded polymers, embossed and formed films, and fusionbonded films [Supracore]), and mesh, for example.

In some examples, the first layer 205 may include a 3D textile, such asvarious textiles commercially available from Baltex, Muller, andHeathcoates. A 3D textile of polyester fibers may be particularlyadvantageous for some embodiments. For example, the first layer 205 maycomprise or consist essentially of a three-dimensional weave ofpolyester fibers. In some embodiments, the fibers may be elastic in atleast two dimensions. A puncture-resistant fabric of polyester andcotton fibers having a weight of about 650 grams per square meter and athickness of about 1-2 millimeters may be particularly advantageous forsome embodiments. Such a puncture-resistant fabric may have a warptensile strength of about 330-340 kilograms and a weft tensile strengthof about 270-280 kilograms in some embodiments. Another particularlysuitable material may be a polyester spacer fabric having a weight ofabout 470 grams per square meter, which may have a thickness of about4-5 millimeters in some embodiments. Such a spacer fabric may have acompression strength of about 20-25 kilopascals (at 40% compression).Additionally or alternatively, the first layer 205 may comprise orconsist of a material having substantial linear stretch properties, suchas a polyester spacer fabric having 2-way stretch and a weight of about380 grams per square meter. A suitable spacer fabric may have athickness of about 3-4 millimeters, and may have a warp and weft tensilestrength of about 30-40 kilograms in some embodiments. The fabric mayhave a close-woven layer of polyester on one or more opposing faces insome examples. In some embodiments, a woven layer may be advantageouslydisposed on a first layer 205 to face a tissue site.

The first layer 205 generally has a first planar surface and a secondplanar surface opposite the first planar surface. The thickness of thefirst layer 205 between the first planar surface and the second planarsurface may also vary according to needs of a prescribed therapy. Forexample, the thickness of the first layer 205 may be decreased torelieve stress on other layers and to reduce tension on peripheraltissue. The thickness of the first layer 205 can also affect theconformability of the first layer 205. In some embodiments, a suitablefoam may have a thickness in a range of about 5 millimeters to 10millimeters. Fabrics, including suitable 3D textiles and spacer fabrics,may have a thickness in a range of about 2 millimeters to about 8millimeters.

The second layer 210 may comprise or consist essentially of a means forcontrolling or managing fluid flow. In some embodiments, the secondlayer 210 may be a fluid control layer comprising or consistingessentially of a liquid-impermeable, elastomeric material. For example,the second layer 210 may comprise or consist essentially of a polymerfilm, such as a polyurethane film. In some embodiments, the second layer210 may comprise or consist essentially of the same material as thecover 125. The second layer 210 may also have a smooth or matte surfacetexture in some embodiments. A glossy or shiny finish better or equal toa grade B3 according to the SPI (Society of the Plastics Industry)standards may be particularly advantageous for some applications. Insome embodiments, variations in surface height may be limited toacceptable tolerances. For example, the surface of the second layer 210may have a substantially flat surface, with height variations limited to0.2 millimeters over a centimeter.

In some embodiments, the second layer 210 may be hydrophobic. Thehydrophobicity of the second layer 210 may vary, but may have a contactangle with water of at least ninety degrees in some embodiments. In someembodiments the second layer 210 may have a contact angle with water ofno more than 150 degrees. For example, in some embodiments, the contactangle of the second layer 210 may be in a range of at least 90 degreesto about 120 degrees, or in a range of at least 120 degrees to 150degrees. Water contact angles can be measured using any standardapparatus. Although manual goniometers can be used to visuallyapproximate contact angles, contact angle measuring instruments canoften include an integrated system involving a level stage, liquiddropper such as a syringe, camera, and software designed to calculatecontact angles more accurately and precisely, among other things.Non-limiting examples of such integrated systems may include the FTÅ125,FTÅ200, FTÅ2000, and FTÅ4000 systems, all commercially available fromFirst Ten Angstroms, Inc., of Portsmouth, Va., and the DTA25, DTA30, andDTA100 systems, all commercially available from Kruss GmbH of Hamburg,Germany. Unless otherwise specified, water contact angles herein aremeasured using deionized and distilled water on a level sample surfacefor a sessile drop added from a height of no more than 5 cm in air at20-25° C. and 20-50% relative humidity. Contact angles herein representaverages of 5-9 measured values, discarding both the highest and lowestmeasured values. The hydrophobicity of the second layer 210 may befurther enhanced with a hydrophobic coating of other materials, such assilicones and fluorocarbons, either as coated from a liquid, or plasmacoated.

The second layer 210 may also be suitable for welding to other layers,including the first layer 205. For example, the second layer 210 may beadapted for welding to polyurethane foams using heat, radio frequency(RF) welding, or other methods to generate heat such as ultrasonicwelding. RF welding may be particularly suitable for more polarmaterials, such as polyurethane, polyamides, polyesters and acrylates.Sacrificial polar interfaces may be used to facilitate RF welding ofless polar film materials, such as polyethylene.

The area density of the second layer 210 may vary according to aprescribed therapy or application. In some embodiments, an area densityof less than 40 grams per square meter may be suitable, and an areadensity of about 20-30 grams per square meter may be particularlyadvantageous for some applications.

In some embodiments, for example, the second layer 210 may comprise orconsist essentially of a hydrophobic polymer, such as a polyethylenefilm. The simple and inert structure of polyethylene can provide asurface that interacts little, if any, with biological tissues andfluids, providing a surface that may encourage the free flow of liquidsand low adherence, which can be particularly advantageous for manyapplications. Other suitable polymeric films include polyurethanes,acrylics, polyolefin (such as cyclic olefin copolymers), polyacetates,polyamides, polyesters, copolyesters, PEBAX block copolymers,thermoplastic elastomers, thermoplastic vulcanizates, polyethers,polyvinyl alcohols, polypropylene, polymethylpentene, polycarbonate,styreneics, silicones, fluoropolymers, and acetates. A thickness between20 microns and 100 microns may be suitable for many applications. Filmsmay be clear, colored, or printed. More polar films suitable forlaminating to a polyethylene film include polyamide, copolyesters,ionomers, and acrylics. To aid in the bond between a polyethylene andpolar film, tie layers may be used, such as ethylene vinyl acetate, ormodified polyurethanes. An ethyl methyl acrylate (EMA) film may alsohave suitable hydrophobic and welding properties for someconfigurations.

As illustrated in the example of FIG. 2, the second layer 210 may haveone or more fluid restrictions 220, which can be distributed uniformlyor randomly across the second layer 210. The fluid restrictions 220 maybe bi-directional and pressure-responsive. For example, each of thefluid restrictions 220 generally may comprise or consist essentially ofan elastic passage that is normally unstrained to substantially reduceliquid flow, and can expand or open in response to a pressure gradient.In some embodiments, the fluid restrictions 220 may comprise or consistessentially of perforations in the second layer 210. Perforations may beformed by removing material from the second layer 210. For example,perforations may be formed by cutting through the second layer 210,which may also deform the edges of the perforations in some embodiments.In the absence of a pressure gradient across the perforations, thepassages may be sufficiently small to form a seal or fluid restriction,which can substantially reduce or prevent liquid flow. Additionally oralternatively, one or more of the fluid restrictions 220 may be anelastomeric valve that is normally closed when unstrained tosubstantially prevent liquid flow, and can open in response to apressure gradient. A fenestration in the second layer 210 may be asuitable valve for some applications. Fenestrations may also be formedby removing material from the second layer 210, but the amount ofmaterial removed and the resulting dimensions of the fenestrations maybe up to an order of magnitude less than perforations, and may notdeform the edges.

For example, some embodiments of the fluid restrictions 220 may compriseor consist essentially of one or more slits, slots or combinations ofslits and slots in the second layer 210. In some examples, the fluidrestrictions 220 may comprise or consist of linear slots having a lengthless than 4 millimeters and a width less than 1 millimeter. The lengthmay be at least 2 millimeters, and the width may be at least 0.4millimeters in some embodiments. A length of about 3 millimeters and awidth of about 0.8 millimeters may be particularly suitable for manyapplications, and a tolerance of about 0.1 millimeter may also beacceptable. Such dimensions and tolerances may be achieved with a lasercutter, for example. Slots of such configurations may function asimperfect valves that substantially reduce liquid flow in a normallyclosed or resting state. For example, such slots may form a flowrestriction without being completely closed or sealed. The slots canexpand or open wider in response to a pressure gradient to allowincreased liquid flow.

The third layer 215 may comprise or consist essentially of a sealinglayer formed from a soft, pliable material suitable for providing afluid seal with a tissue site, such as a suitable gel material, and mayhave a substantially flat surface. For example, the third layer 215 maycomprise, without limitation, a silicone gel, a soft silicone,hydrocolloid, hydrogel, polyurethane gel, polyolefin gel, hydrogenatedstyrenic copolymer gel, a foamed gel, a soft closed cell foam such aspolyurethanes and polyolefins coated with an adhesive, polyurethane,polyolefin, or hydrogenated styrenic copolymers. In some embodiments,the third layer 215 may have a thickness between about 200 microns (μm)and about 1000 microns (μm). In some embodiments, the third layer 215may have a hardness between about 5 Shore 00 and about 80 Shore 00.Further, the third layer 215 may be comprised of hydrophobic orhydrophilic materials.

In some embodiments, the third layer 215 may be a hydrophobic-coatedmaterial. For example, the third layer 215 may be formed by coating aspaced material, such as, for example, woven, nonwoven, molded, orextruded mesh with a hydrophobic material. The hydrophobic material forthe coating may be a soft silicone, for example.

The third layer 215 may have a periphery 225 surrounding or around atreatment aperture 230, and apertures 235 in the periphery 225 disposedaround the treatment aperture 230. The treatment aperture 230 may becomplementary or correspond to a surface area of the first layer 205 insome examples. For example, the treatment aperture 230 may form a frame,window, or other opening around a surface of the first layer 205. Thethird layer 215 may also have corners 240 and edges 245. The corners 240and the edges 245 may be part of the periphery 225. The third layer 215may have an interior border 250 around the treatment aperture 230, whichmay be substantially free of the apertures 235, as illustrated in theexample of FIG. 2. In some examples, as illustrated in FIG. 2, thetreatment aperture 230 may be symmetrical and centrally disposed in thethird layer 215, forming an open central window.

The apertures 235 may be formed by cutting, perforating, or byapplication of local RF or ultrasonic energy, for example, or by othersuitable techniques for forming an opening or perforation in the thirdlayer 215. The apertures 235 may have a uniform distribution pattern, ormay be randomly distributed on the third layer 215. The apertures 235 inthe third layer 215 may have many shapes, including circles, squares,stars, ovals, polygons, slits, complex curves, rectilinear shapes,triangles, for example, or may have some combination of such shapes.

Each of the apertures 235 may have uniform or similar geometricproperties. For example, in some embodiments, each of the apertures 235may be circular apertures, having substantially the same diameter. Insome embodiments, each of the apertures 235 may have a diameter of about1 millimeter to about 50 millimeters. In other embodiments, the diameterof each of the apertures 235 may be about 1 millimeter to about 20millimeters.

In other embodiments, geometric properties of the apertures 235 mayvary. For example, the diameter of the apertures 235 may vary dependingon the position of the apertures 235 in the third layer 215. Forexample, in some embodiments, the apertures 235 disposed in theperiphery 225 may have a diameter between about 5 millimeters and about10 millimeters. A range of about 7 millimeters to about 9 millimetersmay be suitable for some examples. In some embodiments, the apertures235 disposed in the corners 240 may have a diameter between about 7millimeters and about 8 millimeters.

At least one of the apertures 235 in the periphery 225 of the thirdlayer 215 may be positioned at the edges 245 of the periphery 225, andmay have an interior cut open or exposed at the edges 245 that is influid communication in a lateral direction with the edges 245. Thelateral direction may refer to a direction toward the edges 245 and inthe same plane as the third layer 215. As shown in the example of FIG.2, the apertures 235 in the periphery 225 may be positioned proximate toor at the edges 245 and in fluid communication in a lateral directionwith the edges 245. The apertures 235 positioned proximate to or at theedges 245 may be spaced substantially equidistant around the periphery225 as shown in the example of FIG. 2. Alternatively, the spacing of theapertures 235 proximate to or at the edges 245 may be irregular.

As illustrated in the example of FIG. 2, the dressing 110 may furtherinclude an attachment device, such as an adhesive 255. The adhesive 255may be, for example, a medically-acceptable, pressure-sensitive adhesivethat extends about a periphery, a portion, or an entire surface of thecover 125. In some embodiments, for example, the adhesive 255 may be anacrylic adhesive having a coating weight between 25-65 grams per squaremeter (g.s.m.). Thicker adhesives, or combinations of adhesives, may beapplied in some embodiments to improve the seal and reduce leaks. Insome embodiments, such a layer of the adhesive 255 may be continuous ordiscontinuous. Discontinuities in the adhesive 255 may be provided byapertures or holes (not shown) in the adhesive 255. The apertures orholes in the adhesive 255 may be formed after application of theadhesive 255 or by coating the adhesive 255 in patterns on a carrierlayer, such as, for example, a side of the cover 125. Apertures or holesin the adhesive 255 may also be sized to enhance the MVTR of thedressing 110 in some example embodiments.

As illustrated in the example of FIG. 2, in some embodiments, thedressing 110 may include a release liner 260 to protect the adhesive 255prior to use. The release liner 260 may also provide stiffness to assistwith, for example, deployment of the dressing 110. The release liner 260may be, for example, a casting paper, a film, or polyethylene. Further,in some embodiments, the release liner 260 may be a polyester materialsuch as polyethylene terephthalate (PET), or similar polarsemi-crystalline polymer. The use of a polar semi-crystalline polymerfor the release liner 260 may substantially preclude wrinkling or otherdeformation of the dressing 110. For example, the polar semi-crystallinepolymer may be highly orientated and resistant to softening, swelling,or other deformation that may occur when brought into contact withcomponents of the dressing 110, or when subjected to temperature orenvironmental variations, or sterilization. Further, a release agent maybe disposed on a side of the release liner 260 that is configured tocontact the second layer 210. For example, the release agent may be asilicone coating and may have a release factor suitable to facilitateremoval of the release liner 260 by hand and without damaging ordeforming the dressing 110. In some embodiments, the release agent maybe a fluorocarbon or a fluorosilicone, for example. In otherembodiments, the release liner 260 may be uncoated or otherwise usedwithout a release agent.

FIG. 2 also illustrates one example of a fluid conductor 265 and adressing interface 270. As shown in the example of FIG. 2, the fluidconductor 265 may be a flexible tube, which can be fluidly coupled onone end to the dressing interface 270. The dressing interface 270 may bean elbow connector, as shown in the example of FIG. 2, which can beplaced over an aperture 275 in the cover 125 to provide a fluid pathbetween the fluid conductor 265 and the tissue interface 120.

One or more of the components of the dressing 110 may additionally betreated with an antimicrobial agent in some embodiments. For example,the first layer 205 may be a foam, mesh, or non-woven coated with anantimicrobial agent. In some embodiments, the first layer may compriseantimicrobial elements, such as fibers coated with an antimicrobialagent. Additionally or alternatively, some embodiments of the secondlayer 210 may be a polymer coated or mixed with an antimicrobial agent.In other examples, the fluid conductor 265 may additionally oralternatively be treated with one or more antimicrobial agents. Suitableantimicrobial agents may include, for example, metallic silver, PHMB,iodine or its complexes and mixes such as povidone iodine, copper metalcompounds, chlorhexidine, or some combination of these materials.

Additionally or alternatively, one or more of the components may becoated with a mixture that may include citric acid and collagen, whichcan reduce bio-films and infections. For example, the first layer 205may be a foam coated with such a mixture.

FIG. 3 is a top view of the dressing 110 in the example of FIG. 2, asassembled, illustrating additional details that may be associated withsome embodiments. As illustrated in the example of FIG. 2, the cover 125and the third layer 215 may have substantially the same perimeter shapeand dimensions, so that the cover 125 and the third layer 215 arecoextensive in some examples. The cover 125 may be substantiallytransparent, allowing visibility of the apertures 235 in someembodiments. The first layer 205 may be centrally disposed over thethird layer 215, such as over the treatment aperture 230 (not visible inFIG. 3). The cover 125 may be disposed over the first layer 205 andcoupled to the third layer 215 around the first layer 205 so that atleast some of the adhesive 255 can be disposed adjacent to the apertures235.

FIG. 4 is a bottom view of the dressing 110 in the example of FIG. 2, asassembled, illustrating additional details that may be associated withsome embodiments. As illustrated in the example of FIG. 4, a substantialnumber of the fluid restrictions 220 may be aligned or otherwise exposedthrough the treatment aperture 230, and at least some portion of thefirst layer 205 may be disposed adjacent to the fluid restrictions 220opposite the treatment aperture 230. In some embodiments, the firstlayer 205 and the second layer 210 may be substantially aligned with thetreatment aperture 230, or may extend across the treatment aperture 230.

Additionally, the first layer 205 may have a first edge 405, and thesecond layer 210 may have a second edge 410. In some examples, the firstedge 405 and the second edge 410 may have substantially the same shapeso that adjacent faces of the first layer 205 and the second layer 210are geometrically similar. The first edge 405 and the second edge 410may also be congruent in some examples, so that adjacent faces of thefirst layer 205 and the second layer 210 are substantially coextensiveand have substantially the same surface area. In the example of FIG. 4,the first edge 405 defines a larger face of the first layer 205 than theface of the second layer 210 defined by the second edge 410, and thelarger face of the first layer 205 extends past the smaller face of thesecond edge 410.

The faces defined by the first edge 405, the second edge 410, or bothmay also be geometrically similar to the treatment aperture 230 in someembodiments, as illustrated in the example of FIG. 4, and may be largerthan the treatment aperture 230. The third layer 215 may have an overlaymargin 415 around the treatment aperture 230, which may have anadditional adhesive disposed therein. As illustrated in the example ofFIG. 4, the treatment aperture 230 may be an ellipse or a stadium insome embodiments. The treatment aperture 230 may have an area that isequal to about 20% to about 80% of the area of the third layer 215 insome examples. The treatment aperture 230 may also have an area that isequal to about 20% to about 80% of the area of a face of defined by thefirst edge 405 of the first layer 205. A width of about 90 millimetersto about 110 millimeters and a length of about 150 millimeters to about160 millimeters may be suitable for some embodiments of the treatmentaperture 230. For example, the width of the treatment aperture 230 maybe about 100 millimeters, and the length may be about 155 millimeters.In some embodiments, a suitable width for the overlay margin 415 may beabout 2 millimeters to about 3 millimeters. For example, the overlaymargin 415 may be coextensive with an area defined between the treatmentaperture 230 and the first edge 405, and the adhesive may secure thefirst layer 205, the second layer 210, or both to the third layer 215.

FIG. 5 is an assembly view of another example of the dressing 110 ofFIG. 1, illustrating additional details that may be associated with someembodiments. As illustrated in FIG. 5, some examples of the third layer215 may not have the treatment aperture 230, and the apertures 235 maybe distributed in a uniform pattern across the third layer 215.

FIG. 6 is a schematic view of an example of the second layer 210,illustrating additional details that may be associated with someembodiments. As illustrated in the example of FIG. 6, the fluidrestrictions 220 may each consist essentially of one or more slitshaving a length L. A length of about 3 millimeters may be particularlysuitable for some embodiments. FIG. 6 additionally illustrates anexample of a uniform distribution pattern of the fluid restrictions 220.In FIG. 6, the fluid restrictions 220 are substantially coextensive withthe second layer 210, and are distributed across the second layer 210 ina grid of parallel rows and columns, in which the slits are alsomutually parallel to each other. In some embodiments, the rows may bespaced a distance D1. A distance of about 3 millimeters on center may besuitable for some embodiments. The fluid restrictions 220 within each ofthe rows may be spaced a distance D2, which may be about 3 millimeterson center in some examples. The fluid restrictions 220 in adjacent rowsmay be aligned or offset in some embodiments. For example, adjacent rowsmay be offset, as illustrated in FIG. 6, so that the fluid restrictions220 are aligned in alternating rows and separated by a distance D3,which may be about 6 millimeters in some embodiments. The spacing of thefluid restrictions 220 may vary in some embodiments to increase thedensity of the fluid restrictions 220 according to therapeuticrequirements.

FIG. 7 is a schematic view of an example configuration of the apertures235, illustrating additional details that may be associated with someembodiments of the third layer 215. In the example of FIG. 7, theapertures 420 are generally circular and have a diameter D4, which maybe about 6 millimeters to about 8 millimeters in some embodiments. Adiameter D4 of about 7 millimeters may be particularly suitable for someembodiments. FIG. 7 also illustrates an example of a uniformdistribution pattern of the apertures 235. In FIG. 7, the apertures 235are distributed across the third layer 215 in a grid of parallel rowsand columns. Within each row and column, the apertures 235 may beequidistant from each other, as illustrated in the example of FIG. 7.FIG. 7 illustrates one example configuration that may be particularlysuitable for many applications, in which the apertures 235 are spaced adistance D5 apart along each row and column, with an offset of D6. Insome examples, the distance D5 may be about 9 millimeters to about 10millimeters, and the offset D6 may be about 8 millimeters to about 9millimeters.

FIG. 8 is a schematic view of the apertures 235 in the example of FIG. 7overlaid on the second layer 210 of FIG. 6, illustrating additionaldetails that may be associated with some example embodiments of thetissue interface 120. For example, as illustrated in FIG. 8, more thanone of the fluid restrictions 220 may be aligned, overlapping, inregistration with, or otherwise fluidly coupled to the apertures 235 insome embodiments. In some embodiments, one or more of the fluidrestrictions 220 may be only partially registered with the apertures235. The apertures 235 in the example of FIG. 8 are generally sized andconfigured so that at least four of the fluid restrictions 220 isregistered with each one of the apertures 235. In other examples, one ormore of the fluid restrictions 220 may be registered with more than oneof the apertures 235. For example, any one or more of the fluidrestrictions 220 may be a perforation or a fenestration that extendsacross two or more of the apertures 235. Additionally or alternatively,one or more of the fluid restrictions 220 may not be registered with anyof the apertures 235.

As illustrated in the example of FIG. 8, the apertures 235 may be sizedto expose a portion of the second layer 210, the fluid restrictions 220,or both through the third layer 215. The apertures 235 in the example ofFIG. 8 are generally sized to expose more than one of the fluidrestrictions 220. Some or all of the apertures 235 may be sized toexpose two or three of the fluid restrictions 220. In some examples, thelength of each of the fluid restrictions 220 may be substantiallysmaller than the diameter of each of the apertures 235. More generally,the average dimensions of the fluid restrictions 220 are substantiallysmaller than the average dimensions of the apertures 235. In someexamples, the apertures 235 may be elliptical, and the length of each ofthe fluid restrictions 220 may be substantially smaller than the majoraxis or the minor axis. In some embodiments, though, the dimensions ofthe fluid restrictions 220 may exceed the dimensions of the apertures235, and the size of the apertures 235 may limit the effective size ofthe fluid restrictions 220 exposed to the lower surface of the dressing110.

Individual components of the dressing 110 in the examples of FIGS. 2-8may be bonded or otherwise secured to one another with a solvent ornon-solvent adhesive, or with thermal welding, for example, withoutadversely affecting fluid management. Further, the second layer 210 orthe first layer 205 may be coupled to the interior border 250 or theoverlay margin 415 of the third layer 215 in any suitable manner, suchas with a weld or an adhesive, for example.

The cover 125, the first layer 205, the second layer 210, the thirdlayer 215, or various combinations may be assembled before applicationor in situ. For example, the second layer 210 may be laminated to thefirst layer 205 in some embodiments. The cover 125 may be disposed overthe first layer 205 and coupled to the third layer 215 around the firstlayer 205 in some embodiments. In some embodiments, one or more layersof the tissue interface 120 may be coextensive. For example, the secondlayer 210 may be cut flush with the edge of the first layer 205. In someembodiments, the dressing 110 may be provided as a single, compositedressing. For example, the third layer 215 may be coupled to the cover125 to enclose the first layer 205 and the second layer 210, wherein thethird layer 215 may be configured to face a tissue site.

In use, the release liner 260 (if included) may be removed to expose thethird layer 215, which can provide a lower surface of the dressing 110to be placed within, over, on, or otherwise proximate to a tissue site,particularly a surface tissue site and adjacent epidermis. The secondlayer 210, the third layer 215, or both may be interposed between thefirst layer 205 and the tissue site, which can substantially reduce oreliminate adverse interaction between the first layer 205 and the tissuesite. For example, the third layer 215 may be placed over a surfacewound (including edges of the wound) and undamaged epidermis to preventdirect contact with the first layer 205. In some applications, thetreatment aperture 230 of the third layer 215 may be positioned adjacentto, proximate to, or covering a tissue site. In some applications, atleast some portion of the second layer 210, the fluid restrictions 220,or both may be exposed to a tissue site through the treatment aperture230, the apertures 235, or both. The periphery 225 of the third layer215 may be positioned adjacent to or proximate to tissue around orsurrounding the tissue site. The third layer 215 may be sufficientlytacky to hold the dressing 110 in position, while also allowing thedressing 110 to be removed or re-positioned without trauma to the tissuesite.

Removing the release liner 260 can also expose the adhesive 255, and thecover 125 may be attached to an attachment surface, such as theperiphery 225 or other area around the treatment aperture 235 and thefirst layer 205. The adhesive 255 may also be attached to epidermisperipheral to a tissue site, around the first layer 205 and the secondlayer 210. For example, the adhesive 255 may be in fluid communicationwith an attachment surface through the apertures 235 in at least theperiphery 225 of the third layer 215. The adhesive 255 may also be influid communication with the edges 245 through the apertures 235 exposedat the edges 245.

Once the dressing 110 is in the desired position, the adhesive 255 maybe pressed through the apertures 235 to bond the dressing 110 to theattachment surface. The apertures 235 at the edges 245 may permit theadhesive 255 to flow around the edges 245 for enhancing the adhesion ofthe edges 245 to an attachment surface.

In some embodiments, the apertures 235 may be sized to control theamount of the adhesive 255 exposed through the apertures 235. For agiven geometry of the corners 240, the relative sizes of the apertures235 may be configured to maximize the surface area of the adhesive 255exposed and in fluid communication through the apertures 235 at thecorners 240. For example, the edges 245 may intersect at substantially aright angle, or about 90 degrees, to define the corners 240. In someembodiments, the corners 240 may have a radius of about 10 millimeters.Further, in some embodiments, three of the apertures 235 may bepositioned in a triangular configuration at the corners 240 to maximizethe exposed surface area for the adhesive 255. In other embodiments, thesize and number of the apertures 235 in the corners 240 may be adjustedas necessary, depending on the chosen geometry of the corners 240, tomaximize the exposed surface area of the adhesive 255. Further, theapertures 235 at the corners 240 may be fully contained within the thirdlayer 215, substantially precluding fluid communication in a lateraldirection exterior to the corners 240. The apertures 235 at the corners240 being fully contained within the third layer 215 may substantiallypreclude fluid communication of the adhesive 255 exterior to the corners240, and may provide improved handling of the dressing 110 duringdeployment at a tissue site. Further, the exterior of the corners 240being substantially free of the adhesive 255 may increase theflexibility of the corners 240 to enhance comfort.

In some embodiments, the bond strength of the adhesive 255 may varybased on the configuration of the third layer 215. For example, the bondstrength may vary based on the size of the apertures 235. In someexamples, the bond strength may be inversely proportional to the size ofthe apertures 235. Additionally or alternatively, the bond strength mayvary in different locations, for example, if the size of the apertures235 varies. For example, a lower bond strength in combination withlarger apertures 235 may provide a bond comparable to a higher bondstrength in locations having smaller apertures 235.

The geometry and dimensions of the tissue interface 120, the cover 125,or both may vary to suit a particular application or anatomy. Forexample, the geometry or dimensions of the tissue interface 120 and thecover 125 may be adapted to provide an effective and reliable sealagainst challenging anatomical surfaces, such as an elbow or heel, atand around a tissue site. Additionally or alternatively, the dimensionsmay be modified to increase the surface area for the third layer 215 toenhance the movement and proliferation of epithelial cells at a tissuesite and reduce the likelihood of granulation tissue in-growth.

Thus, the dressing 110 can provide a sealed therapeutic environmentproximate to a tissue site, substantially isolated from the externalenvironment, and the negative-pressure source 105 can reduce thepressure in the sealed therapeutic environment. The treatment aperture230 can provide an open area for delivery of negative pressure andpassage of wound fluid through the second layer 210 and the first layer205. The third layer 215 may provide an effective and reliable sealagainst challenging anatomical surfaces, such as an elbow or heel, atand around a tissue site. Further, the dressing 110 may permitre-application or re-positioning, to correct air leaks caused by creasesand other discontinuities in the dressing 110, for example. The abilityto rectify leaks may increase the efficacy of the therapy and reducepower consumption in some embodiments.

If not already configured, the dressing interface 270 may be disposedover the aperture 275 and attached to the cover 125. The fluid conductor265 may be fluidly coupled to the dressing interface 270 and to thenegative-pressure source 105.

Negative pressure applied through the tissue interface 120 can create anegative pressure differential across the fluid restrictions 220 in thesecond layer 210, which can open or expand the fluid restrictions 220.For example, in some embodiments in which the fluid restrictions 220 maycomprise substantially closed fenestrations through the second layer210, a pressure gradient across the fenestrations can strain theadjacent material of the second layer 210 and increase the dimensions ofthe fenestrations to allow liquid movement through them, similar to theoperation of a duckbill valve. Opening the fluid restrictions 220 canallow exudate and other liquid movement through the fluid restrictions220 into the first layer 205. The first layer 205 can provide passage ofnegative pressure and wound fluid, which can be collected in thecontainer 115. Changes in pressure can also cause the first layer 205 toexpand and contract, and the second layer 210, the third layer 215, orboth may protect the epidermis from irritation that could be caused byexpansion, contraction, or other movement of the first layer 205. Forexample, in some embodiments, the overlay margin 415 may be disposedbetween the first layer 205 and epidermis around a tissue site. Thesecond layer 210 and the third layer 215 can also substantially reduceor prevent exposure of a tissue site to the first layer 205, which caninhibit growth of tissue into the first layer 205. For example, thesecond layer 210 may cover the treatment aperture 230 to prevent directcontact between the first layer 205 and a tissue site.

If the negative-pressure source 105 is removed or turned off, thepressure differential across the fluid restrictions 220 can dissipate,allowing the fluid restrictions 220 to close and prevent exudate orother liquid from returning to the tissue site through the second layer210.

In some applications, a filler may also be disposed between a tissuesite and the third layer 215. For example, if the tissue site is asurface wound, a wound filler may be applied interior to the periwound,and the third layer 215 may be disposed over the periwound and the woundfiller. In some embodiments, the filler may be a manifold, such as anopen-cell foam. The filler may comprise or consist essentially of thesame material as the first layer 205 in some embodiments.

Additionally or alternatively, instillation solution or other fluid maybe distributed to the dressing 110, which can increase the pressure inthe tissue interface 120. The increased pressure in the tissue interface120 can create a positive pressure differential across the fluidrestrictions 220 in the second layer 210, which can open the fluidrestrictions 220 to allow the instillation solution or other fluid to bedistributed to the tissue site.

The systems, apparatuses, and methods described herein may providesignificant advantages. For example, some dressings fornegative-pressure therapy can require time and skill to be properlysized and applied to achieve a good fit and seal. In contrast, someembodiments of the dressing 110 provide a negative-pressure dressingthat is simple to apply, reducing the time to apply and remove. In someembodiments, for example, the dressing 110 may be a fully-integratednegative-pressure therapy dressing that can be applied to a tissue site(including on the periwound) in one step, without being cut to size,while still providing or improving many benefits of othernegative-pressure therapy dressings that require sizing. Such benefitsmay include good manifolding, beneficial granulation, protection of theperipheral tissue from maceration, protection of the tissue site fromshedding materials, and a low-trauma and high-seal bond. Thesecharacteristics may be particularly advantageous for surface woundshaving moderate depth and medium-to-high levels of exudate. Someembodiments of the dressing 110 may remain on the tissue site for atleast 5 days, and some embodiments may remain for at least 7 days.Antimicrobial agents in the dressing 110 may extend the usable life ofthe dressing 110 by reducing or eliminating infection risks that may beassociated with extended use, particularly use with infected or highlyexuding wounds.

While shown in a few illustrative embodiments, a person having ordinaryskill in the art will recognize that the systems, apparatuses, andmethods described herein are susceptible to various changes andmodifications that fall within the scope of the appended claims.Moreover, descriptions of various alternatives using terms such as “or”do not require mutual exclusivity unless clearly required by thecontext, and the indefinite articles “a” or “an” do not limit thesubject to a single instance unless clearly required by the context.Components may be also be combined or eliminated in variousconfigurations for purposes of sale, manufacture, assembly, or use. Forexample, in some configurations the dressing 110, the container 115, orboth may be eliminated or separated from other components formanufacture or sale. In other example configurations, the controller 130may also be manufactured, configured, assembled, or sold independentlyof other components.

The appended claims set forth novel and inventive aspects of the subjectmatter described above, but the claims may also encompass additionalsubject matter not specifically recited in detail. For example, certainfeatures, elements, or aspects may be omitted from the claims if notnecessary to distinguish the novel and inventive features from what isalready known to a person having ordinary skill in the art. Features,elements, and aspects described in the context of some embodiments mayalso be omitted, combined, or replaced by alternative features servingthe same, equivalent, or similar purpose without departing from thescope of the invention defined by the appended claims.

1. A dressing for treating a tissue site with negative pressure, thedressing comprising: a sealing layer comprising a treatment aperture anda plurality of perforations around the treatment aperture; a fluidcontrol layer comprising a plurality of fluid restrictions aligned withthe treatment aperture; a manifold adjacent to the fluid restrictions;and a cover comprising a film and a pressure-sensitive adhesive, thefilm disposed over the manifold and coupled to the sealing layer aroundthe manifold, and the pressure-sensitive adhesive disposed adjacent tothe plurality of perforations.
 2. The dressing of claim 1, wherein thefluid control layer comprises a film of polyurethane.
 3. The dressing ofclaim 2, wherein the fluid restrictions comprise slits in the film. 4.The dressing of claim 3, wherein the slits each have a length in a rangeof about 2 millimeters to about 5 millimeters.
 5. The dressing of claim3, wherein the slits each have a length of about 3 millimeters.
 6. Thedressing of claim 1, wherein the sealing layer is formed from a gel. 7.The dressing of claim 1, wherein the sealing layer is formed from asilicone gel.
 8. The dressing of claim 1, wherein: the manifold has afirst edge defining a manifold face adjacent to the fluid control layer;the fluid control layer has a second edge defining a fluid control faceadjacent to the manifold face and having a similar shape to the manifoldface; and the manifold face is at least as large as the fluid controlface.
 9. The dressing of claim 8, wherein the fluid control face islarger than the treatment aperture.
 10. The dressing of claim 1, whereinat least one of the manifold and the fluid control layer is coupled to amargin around the treatment aperture.
 11. The dressing of claim 10,wherein the margin has a width in a range of about 2 millimeters toabout 3 millimeters.
 12. The dressing of claim 1, wherein the treatmentaperture is complementary to the manifold.
 13. The dressing of claim 1,wherein the treatment aperture forms a window around the manifold. 14.The dressing of claim 1, wherein the treatment aperture has a width in arange of about 90 millimeters to about 110 millimeters and a length in arange of about 150 millimeters to about 160 millimeters.
 15. A dressingfor treating a tissue site with negative pressure, the dressingcomprising: a manifold; a fluid control layer comprising a plurality offluid restrictions adjacent to the manifold; a gel layer comprising aplurality of perforations, wherein at least some of the perforations arealigned with more than one of the fluid restrictions; and a covercomprising a non-porous film and a pressure-sensitive adhesive, thenon-porous film disposed over the manifold and coupled to the gel layeraround the manifold, and the pressure-sensitive adhesive disposedadjacent to the plurality of perforations.
 16. The dressing of claim 15,wherein the perforations are circular and have a diameter in a range ofabout 7 millimeters to about 9 millimeters.
 17. The dressing of claim15, wherein the fluid control layer comprises a film of polyurethane.18. The dressing of claim 17, wherein the fluid restrictions compriseslits in the film of polyurethane.
 19. The dressing of claim 18, whereinthe slits each have a length in a range of about 2 millimeters to about5 millimeters.
 20. The dressing of claim 19, wherein the slits each havea length of about 3 millimeters.
 21. The dressing of claim 15, whereinthe perforations are circular and have a diameter in a range of about 7millimeters to about 9 millimeters.
 22. A dressing for treating a tissuesite with negative pressure, the dressing comprising: a cover having anadhesive; a manifold; a perforated polymer film; and a perforatedsilicone gel having a treatment aperture; wherein the cover, themanifold, the perforated polymer film, and the perforated silicone gelare assembled in a stacked relationship with the cover and theperforated silicone gel enclosing the manifold, the perforated polymerfilm is at least partially exposed through the treatment aperture, andat least some of the adhesive is exposed through the perforated siliconegel around the treatment aperture.
 23. The dressing of claim 22, whereinthe treatment aperture corresponds to a surface of the manifold.
 24. Thedressing of claim 22, wherein the treatment aperture forms a framearound the manifold.
 25. The dressing of claim 1, wherein the treatmentaperture has a width in a range of about 90 millimeters to about 110millimeters and a length in a range of about 150 millimeters to about160 millimeters.
 26. A dressing for treating a tissue site with negativepressure, the dressing comprising: a manifold; a gel layer comprising anopen central window and a plurality of openings around the open centralwindow; a fluid control layer extending across the open central windowand comprising a plurality of fluid restrictions; and a cover comprisinga film and a pressure-sensitive adhesive, the film disposed over themanifold and coupled to the gel layer around the manifold, and thepressure-sensitive adhesive disposed adjacent to the plurality ofopenings.
 27. The dressing of claim 26, wherein the open central windowcomprises an opening in the gel layer of about 20% to about 80%.
 28. Thedressing of claim 26, wherein the open central window has a width in arange of about 90 millimeters to about 110 millimeters and a length in arange of about 150 millimeters to about 160 millimeters.
 29. Thedressing of claim 26, wherein the open central window comprises anopening that allows fluid ingress through the fluid control layer. 30.The dressing of claim 26, wherein the open central window has an areawithin 20% of a surface area of the manifold proximate to the opencentral window.
 31. A dressing for treating a tissue site with negativepressure, the dressing comprising: a foam manifold for the passage ofnegative pressure and passage of wound fluid; a lower surface having anopen area for delivery of negative pressure and passage of wound fluidvia the manifold; a drape area surrounding the open area, the drape areahaving an adhesive for sealing to tissue and not including openings forthe passage of negative pressure via the manifold; and a polymer filmwound contact layer extending across the open area in the lower surfaceand having openings for the passage of negative pressure and wound fluidinto the foam manifold.
 32. The dressing of claim 31, wherein thedressing further comprises a cover comprising a drape disposed over themanifold and coupled to the drape area around the manifold. 33.(canceled)